Process for the manufacture of neutral polyphosphoric acid esters by reacting phosphorus pentoxide and boric acid esters

ABSTRACT

A PROCESS HAS BEEN PROVIDED FOR PRODUCING NEUTRAL POLYPHOSPHORIC ACID ESTER DERIVATIVES WHICH COMPRISES REACTING AN ACID ESTER WITH PHOSPHORUS PENTOXIDE AT A TEMPERATURE WITHIN THE RANGE OF-78*C. TO - 140*C. IN THE ABSENCE OF MOISTURE AND IN A MOLE RATIO OF ESTER TO PHOSPHORUS PENTOXIDE FROM 0.05 TO 9 MOLES ESTER TO 1 MOLE PHOSPHORUS PENTOXIDE, SAID ACID ESTER BEING DEFINED BY THE GENERAL FORMULA   (R&#39;&#39;,MB-(OR)A   R&#34;M   WHEREIN 1+M+N 3 IN WHICH FORMULA R REPRESENTS A SATURATED, UNSTARUATED, OXALKYLATED, OF HALOGENATED ALIPHATIC RADICAL OF 1 TO 12 CARBON ATOMS, OR AN AROMATIC RADICAL OF 1 TO 12 CARBON ATOMS. R! AND R&#34; EACH REPRESENTS A HYDROGEN A SATURATED, UNSTAURATED, OXALKYLATED, OR HALOGENATED ALIPHATIC OR CYCLOALIPHATIC RADICAL OF 1 TO 12 CARBON ATOMS OR AN AROMATIC RADICAL OF 1 TO 12 CARBON ATOMS. THESE COMPOUNDS ARE USEFUL AS CATALYSTS FOR PRODUCTIN OF PLYACETALS.

United States Patent US. Cl. 260922 2 Claims ABSTRACT OF THE DISCLOSUREA process has been provided for producing neutral polyphosphoric acidester derivatives which comprises reacting an acid ester with phosphoruspentoxide at a temperature within the range of -78 C. to +140 C., in theabsence of moisture and in a mole ratio of ester to phosphorus pentoxidefrom 0.05 to 9 moles ester to 1 mole phosphorus pentoxide, said acidester being defined by the general formula wherein 1+m+n=3 in whichformula R represents a saturated, unsaturated, oxalkylated, orhalogenated aliphatic radical of 1 to 12 carbon atoms, or an aromaticradical of 1 to 12 carbon atoms, R and R each represents a hydrogen, asaturated, unsaturated, oxalkylated, or halogenated aliphatic orcycloaliphatic radical of 1 to 12 carbon atoms or an aromatic radical of1 to 12 carbon atoms. These compounds are useful as catalysts forproduction of polyacetals.

This application is a division of application Ser. No. 504,187, filedOct. 23, 1965, now abandoned.

The present invention relates to a process for the manufacture ofneutral polyphosphoric acid ester derivatives.

It is known that neutral. polyphosphoric acid esters can be obtained byreacting alkyl or aryl esters of phosphoric acid with phosphoruspentoxide whereby oily compounds are formed which cannot be distilled.This process has the disadvantage that the unreacted proportions of thestarting products can be separated from the reaction product only withdifficulty at elevated temperatures. At temperatures above 120 C.,however, neutral polyphosphoric acid esters, except methyl esters, beginto decompose. The said process is not, therefore, suited for themanufacture of polyphosphoric acid esters that are free from phosphateand phosphoric or polyphosphoric acid. It is furthermore known thattetrameric cyclic polyphosphoric acid esters are formed by the reactionof phosphorus pentoxide with diethyl ether in chloroform. In thisprocess, a definite mixture of two known compounds is formed; thereaction requires, however, a relatively long time, which isinconvenient especially for the manufacture of relatively large amountsof these polyphosphoric acid esters. Moreover, the course of thereaction depends to a large extent on the quality of the phosphoruspentoxide used.

Now we have found that derivatives of polyphosphoric acid esters can beobtained in an advantageous manner by reacting nonmetallic acid estersof nonmetals of Groups III, IV and VI of the Mendeleff Periodic Table ormixtures of these nonmetallic acid esters, if desired in the presence ofa solvent, at a temperature within the range of 78 C. and 140 C. withphosphorus pentoxide.

The term nonmetallic acid esters is used herein to mean compounds of theelements boron, carbon, silicon 3,644,596 Patented Feb. 22, 1972 andsulfur which correspond to one of the following Formulae I to IV,

in which R represents a saturated or unsaturated, oxalkylated orhalogenated aliphatic radical or an aromatic radical, R and R eachrepresent a saturated or unsaturated, oxalkylated or halogenatedaliphatic or cycloaliphatic radical or an aromatic radical. In FormulaII, R may also represent a hydrogen atom, R, R and R may be identical ordifferent and may each contain 1 to 12 carbon atoms. As oxalkylatedaliphatic radicals there are advantageously used methoxy, ethoxy,propoxy or butoxyalkyl radicals. As halogenated aliphatic radicals,mono-halo-alkyl groups may be advantageously used. Furthermore, in theabove Formulae I to IV, j, k, l, m and n are whole numbers or zero andmust be such that the equations given below the said formulae befulfilled, and It must be greater than zero in Formulae I, II and IV; inFormula III x is a whole or fractional number of at least one.Fractional numbers are obtained when, in the case 0 of polyorthosilicicacid esters, mixtures of such esters are R'SO' (OR) in which R, R and R"have the meanings given above.

Nonmetallic acid esters particularly suitable for use are, for example,compounds of the formula RR"Si(OR) in which R, R. and R represent methylor ethyl groups, or mixtures of such compounds. There may further beused hexaethyl-di-orthosilicate and ethylpoly-orthosilicate. It is alsopossible to use trimethyl, triethyl or tripropyl esters of orthoboricacid or the corresponding esters of alkylboric acids in which the alkylgroup contains 1 to 4 carbon atoms, or mixtures of such compounds forthe reaction with phosphorus pentoxide.

The nonmetallic acid esters are added in a pure state or in the presenceof one of the solvents indicated below at a temperature within the rangeof 78 C. to +140 C., advantageously 30 C. to C., preferably under aninert gas, for example nitrogen, and with as complete an exclusion ofmoisture as possible, to phosphorus pentoxide in a pure state or in theform of a mixture thereof with one of the solvents named below. Thereaction mixture so obtained is stirred or vigorously mixed thoroughlyat a temperature within the range indicated above. The reaction timedepends on the reactivity of the nonmetallic acid ester and the reactiontemperature and varies within a few minutes (about 3 to 10 minutes) andabout 48 hours. The nonmetallic acid ester is advantageously used in amolar ratio within the range of 0.005 to 20 moles, advantageously themolar amounts set forth in the tables given below for each mole ofphosphorus pentoxide.

In the first column of the table, the type of non-metallic acid esterused is indicated, R, R and R" having the meaings given above. Thesecond column indicates the range of the molar amounts of thenonmetallic acid esters within which the nonmetallic acid ester isreacted, for example, with 1 mole of phosphorus pentoxide.Polyorthosilicic acid alkyl esters, in which the alkyl groups may rangefrom methyl to n-pentyl groups, are used in an amount of 0.25 to 3 unitsof weight for each unit of weight of phosphorus pentoxide.

TABLE Range of molar amounts Type of nonmetallic of nonmetallic acid Assolvents, halogenated hydrocarbons boiling between 35 C. and 120 C. maybe used. Advantageously chloroform, methylene chloride or1,1,1-trichloroethane are used. It is, however, also possible to carryout the reaction in the presence of, for example, carbon tetrachloride,methylene bromide, symmetrical or asymmetrical dichlorethane,1,1,2-trichlorethane, trichlorethylene, tetrachlorethylene,trifluorotrichlorethane or symmetrical difluorotetrachlorethane ormixtures of these compounds. The solvents are advantageously used in ananhydrous or alcohol-free state in an amount within the range of 1 to300 parts by weight, advantageously 7 to 50 parts by weight, for eachpart by weight of phosphorus pentoxide.

It is advantageous to carry out the reaction and also the work-up withas complete an exclusion of moisture as possible.

The polyphosphoric acid ester derivatives formed are obtained after thereaction in the form of a solution or, if the reaction is carried outwithout a solvent, in the form of viscous oils intermingled withunreacted P In the latter case it is advantageous to dissolve the oilsby adding a solvent since solutions can be worked up particularly Well.The solutions can be separated from the solid sub-stance by suctionfiltration and freed from solvent and unreacted nonmetalic acid esterunder reduced or strongly reduced pressure at a temperature of the bathof below 110 C. It is also possible to precipitate the dissolvedpolyphosphoric acid ester derivatives by adding a liquid precipitatingagent. The supernatant solvent containing the unreacted proportions ofstarting product and other impurities, is decanted. This procedure ofdissolving and precipitation may be repeated as often as desired toremove undesirable impurities substantially quantitatively from thepolyphosphoric acid ester derivatives. As precipitating agents, lowmolecular weight alkanes and cycloalkanes with 5 to 12 carbon atomswhich are liquid at room temperature may advantageously be used.Examples of such compounds are hexane, heptane, octane and cyclohexane.Aliphatic or cyclic ethers, for example, diethyl ether,tetrahydrofurane, glycol dimethyl ether, dioxane and benzene may also beused as precipitating agents. The nonmetallic acid esters are in generalsulficiently soluble in the organic solvents used as precipitatingagents and are highly soluble in the solvent mixtures comprisinghalogenated hydrocarbons and precipitating agents, which are formed inthe precipitating process. The precipitation of dissolved polyphosphoricacid ester derivatives may also be used for fractionating the productsby precipitating fractions with different degrees of solubility oneafter the other by adding different amounts of precipitating agent.Fractions that have been obtained in this manner differ from one anotherwith respect to their catalytic activity. The polyphosphoric acid esterderiva tives are obtained in the form a colourless to slightly yellowishviscous oil which cannot be distilled or in the form of an amorphoussolid mass.

The polyphosphoric acid ester derivatives constitute mixed anhydrides ofpartially hydrolyzed polyphosphoric acid esters with partially orcompletely hydrolyzed nonmetallic acid esters. These mixed anhydridescontain a mixture of open-chain, cyclic and combined open-chain/ cyclicmolecules with polyphosphate structures in whichphosphorus-oxygen-nonmetal bonds are statistically distributed. Thecontent of such P-O-nonmetal groupings depends chiefiy on the molarratio in which the starting products have been reacted with one another.It is, however, also influenced by the reaction temperature and dependsalso on the individual nonmetals themselves. The nonmetal atom in themixed polyphosphoric acid ester anhydrides may be linked to phosphorusatoms via all singlebond oxygen functions present in the nonmetallicacid ester or via only a part of these oxygen bonds. In the latter casethe remaining nonmetal-oxygen-single bonds still carry the radicalspresent in the starting ester. The following general formulae representtwo of the numerous possible molecule sections of such polyphosphoricacid ester anhydrides, radicals R and R having the meanings given above.

ll 1+m+n=valence of 0 the nonmetal The nonmetallic acid esters partiallygive off their OR groups only for the splitting of the P 0 structureinto neutral polyphosphoric acid ester parts, the nonmetal parent atomnot being incorporated in or added to the polymer phosphate. The extentof this type of reaction depends on the reaction conditions and is mostpronounced in sulfites. The elementary composition of the polyphosphoricacid ester anhydrides depends, therefore, not only on the molar ratio ofthe starting components but may vary strongly with the reactionconditions and the type of nonmetal used.

As compared with the known neutral polyphosphoric acid esters, the mixedpolyphosphoric acid ester anhydrides of the invention have aconsiderably improved catalytic action when used, instead of acids orLewis acids, as catalysts for proton-catalyzed reactions. Moreover, thecatalytic action of the polyphosphoric acid ester anhydrides obtained inaccordance with the invention can be graduated by means of a differentcontent of nonmetals other than phosphorus.

The mixed polyphosphoric acid ester anhydrides made in accordance withthe invention can be used as catalysts for proton-catalyzed reactionssuch as, for example, biochemical polycondensation reactions orpolymerization reactions, for example, in the field of polyacetals. Theymake also appropriate intermediates for the manufacture of insecticides.

The following examples serve to illustrate the invention but they arenot intended to limit it thereto.

EXAMPLE 1 6.97 grams (49 millimoles) phosphorus pentoxide and 20 cc.pure chloroform were introduced into a groundglass flask of a capacityof 100 cc. under an atmosphere of dry nitrogen and with the exclusion ofmoisture. The reaction mixture so obtained was kept on a bath having atemperature of ;+20 C. and 3.5 grams (24 millimoles) triethyl boratewere quickly added dropwise from a pipet, while shaking. The reactionmixture was kept for about 30 minutes on the bath having a temperatureof 20 C., while shaking occasionally. The bath was then withdrawn andshaking was continued for a further 6 hours at room temperature. Thereaction mixture was then separated from undissolved proportions bysuction filtration and the solution was concentrated by evaporationunder a reduced pressure of 3 millimeters of mercury on a bath having atemperature of 50 C. until a constant weight was obtained, 9.3 grams ofa tough colourless glassy mass which was readily soluble in the usualchlorinated hydrocarbons were obtained.

Composition in percent: B, 3.3; P, 24.7; C, 21.4; H, 4.6

EXAMPLE 2 Under the conditions of Example 1, 18.3 grams (125 millimoles)triethyl borate were added to a mixture of 17.82 grams (125 millimoles)phosphorus pentoxide and 40 cc. chloroform. The mixture so obtained wasshaken for 24 hours at room temperature until substantially all of thephosphorus pentoxide had undergone reaction. To facilitate filtrationthe reaction mixture was diluted with 50 cc. chloroform andsuction-filtered. The filtrate was concentrated in vacuo on a 'bathhaving a temperature of 50 C. 25.5 grams of a tough colourless glassyproduct were obtained.

Composition in percent: B, 3.3; P, 22.8; C, 23.0; H, 5.1.

EXAMPLE 3 12.5 grams of the colourless glassy product obtained by thereaction described in Example 2 were dissolved in 30 cc. chloroform. Tothe solution so obtained 30 cc. heptane were added while shaking,whereby "a white amorphous product (fraction I) was graduallyprecipitated. The supernatant solution was decanted. The amorphousresidue was shaken with 50 cc. of a mixture of 5 parts by volume ofheptane and 1 part by volume of chloroform and allowed to deposit andthe solution was decanted. This procedure was carried out three times.The amorphous residue was freed from solvent in vacuo at a temperatureof the bath of 50 C. 7.0 grams of an amorphous solid white product whichwas very hygroscopic and deliquesced rapidly in the air (fraction I)were obtained.

Composition in percent: B, 4.8; P, 19.7; C, 18.9; H, 4.3.

To the solution which had been decanted in the precipitation of fractionI 30 cc. heptane were added whereby further proportions of a solidamorphous product (fraction II) were precipitated. Fraction II wasworked up and washed in the same manner as fraction I. By evaporatingthe solvent in vacuo at a temperature of the bath of 50 C., a solidamorphous mass which was deliquescent in the air was obtained (fractionII).

Composition in percent: B, 4.7; P, 8.5; C, 18.0; H, 4.8.

EXAMPLE 4 Under the conditions described in Example 1, 4 grams (21millimoles) tri-n-propyl borate were added to a mixture of 6.2 grams (43millimoles) phosphorus pentoxide and 30 cc. chloroform. The reactionmixture so obtained was heated overnight at +40 C., while stirring. The

reaction mixture was then suction-filtered and the filtrate wasconcentrated in vacuo at a temperature of the bath of 40 C., until aconstant weight was obtained. 7.3 grams of a tough slightly yellowishglassy mass which was easily soluble in chloroform were obtained.

Composition in percent: B, 3.1; P, 18.2; C, 31.3; H, 6.4.

EXAMPLE 5 In the manner described in Example 1, 8.56 grams (37millimoles) tri-n-butyl-borate were added to a mixture of 5.25 grams (37millimoles) phosphorus pentoxide and 30 cc. methylene chloride. Thewhole was shaken overnight at 20 C. and then worked up as described inExample 1. By evaporating under a pressure of 0.1 millimeter of mercuryat a temperature of the bath of 35 C. until a constant weight had beenobtained, 12.55 grams of a tough colourless glassy product wereobtained. The product was very easily soluble in the usual chlorinatedhydrocarbons and in mixtures of such compounds with, for example,heptane in a proportion by volume of 1:8.

Composition in percent: B, 2.9; P, 17.7; C, 36.2; H, 7.1.

A sample heated for 10 hours at 90 C. under a pressure of 0.1 millimeterof mercury had the following composition as determined by analysis: B,3.1%; P, 17.8%; C, 36.0%; H, 6.9%. Consequently, the polyphosphoric acidester derivative was not decomposed at that temperature.

EXAMPLE 6 In the manner described in Example 1, 10.5 grams (45millimoles) tris-[2-methoxyethyl]-borate were added to a mixture of 6.46grams (45 millimoles) phosphorus pentoxide and 2 0 cc. chloroform. Thereaction mixture acquired 'a slightly yellowish colouration and washeated for 24 hours at 40 C. The phosphorus pentoxide was not dissolvedcompletely. The reaction mixture was suctionfiltered and the solutionwas concentrated to about 15 cc. 60 cc. heptane were added whereby acolourless oil was precipitated. The supernatant solution was poured offand the oil remaining behind was digested twice with 50 cc. of a mixtureof 5 parts by volume of heptane and 1 part by volume of chloroform. Theresidual proportions of solvent were removed by heating in vacuo at 40C. 6.2 grams of a colourless amorphous mass were obtained.

Composition in percent: B, 3.6; P, 8.4; C, 36.3; H, 7.4.

EXAMPLE 7 Under the conditions described in Example 1, 13.8 grams (47.5millimoles) triphenyl borate were added to a mixture of 6.77 grams (47.5millimoles) P 0 and 30 cc. chloroform and the whole was heated for 24hours at C. The reaction mixture was then separated from the brown solidsubstance by suction filtration. The solution was concentrated to 10 cc.and 100 cc. heptane were added. A yellowish oil precipitated which,after decantation of the supernatant solution, was washed and freed fromsolvent in vacuo as described in Example 6. 16.2 grams of a yellowishamorphous mass were obtained.

Composition in percent: B, 3.0; P, 12.9; C, 50.2; H, 4.1.

EXAMPLE 8 2.93 grams (16 millimoles) triallyl borate were added at 20C., under dry nitrogen, to a mixture of 5.10 grams (36 millimoles)phosphorus pentoxide and 30 cc. chloroform and the whole was shaken at 0C. for 48 hours. The reaction mixture acquired a brown colour; thereaction with P 0 was incomplete since the P 0 was was superficiallycovered with small amounts of resinous by-products which formed and thusimpeded a further reaction. The reaction mixture was suction-filteredand the solution was concentrated in vacuo to 20 cc. and admixed withcc. heptane. A yellow-brown oil precipitated. It was washed and freedfrom solvent as described in Example 6. 4.1 grams of a brownish viscousoil were obtained.

Composition in percent: P, 11.1; C, 35.5; H, 5.6.

EXAMPLE 9 7.3 grams (50 millimoles) triethyl borate and 11.5 grams (50millimoles) tri-n-butyl borate were added to a mixture, kept at -10 C.,of 10.32 grams (75 millimoles) phosphorus pentoxide and 50 cc. methylenechloride. The phosphorus pentoxide dissolved completely within a fewminutes. After having been kept at --10 C. for about 30 minutes, thereaction mixture was shaken for a further 3 hours at room temperature.The reaction mixture was then concentrated under a pressure of 0.1millimeter of mercury at a temperature of the bath of 40 C. until aconstant weight was obtained. 17.9 grams of a viscous colourless oilwere obtained.

Composition in percent: B, 3,6; P, 18.3; C, 25.7; H, 5.6.

EXAMPLE 10 Under the conditions of Example 1, 1.53 grams (15 millimoles)ethylboric acid dimethyl ester were added to a mixture at C. of 4.25grams (30 millimoles) phosphorus pentoxide and 10 cc. methylenechloride. After 30 minutes the temperature of the reaction mixture wasallowed to rise to room temperature and the reaction mixture was shakenat that temperature for 4 hours. The reaction mixture was then separatedfrom undissolved proportions by suction filtration and the solution wasconcentrated as described in Example 9. 4.6 grams of a viscouscolourless oil were obtained.

Composition in percent: B, 2.7; P, 25.3; C, 22.3; H, 4.9.

EXAMPLE 11 In the manner described in Example 10, 1.78 grams (10millimoles) phenylboric acid diethyl ester were added at 0 C. to amixture of 5.37 grams (38 millimoles) phosphorus pentoxide and 30 cc.methylene chlo ride and the whole was shaken vigorously. After 10minutes, the temperature of the reaction mixture was allowed to rise toroom temperature and the reaction mixture was shaken at that temperaturefor a further 6 hours. The reaction mixture was then diluted with 50 cc.methylene chloride and separated from undissolved proportions by suctionfiltration. The solution was concentrated in vacuo to about 10 cc. and70 cc. hexane were added, whereby an amorphous white product wasprecipitated. The latter was washed like the solid fractions describedin Example 3 and freed from residual proportions of solvent by drying invacuo at a temperature of the bath of 60 C.

The product contained 1.3% of boron.

EXAMPLE 12 2.13 grams (11 millimoles) tetraethyl orthocarbonate wereadded dropwise under nitrogen, while stirring, to a mixture at -30 C. of3.14 grams (22 millimoles) phosphorus pentoxide and 10 cc. chloroform.After 10 minutes, the temperature of the reaction mixture was allowed torise to room temperature and the mixture was then heated for 4 hours at60 C. The reaction mixture was separated from small proportions ofunreacted P 0 by suction filtration and the solution was then evaporatedunder a pressure of 0.1 millimeter of mercury at a temperature of thebath of 70 C. until a constant weight was obtained. About 4 grams of aviscous colourless oil were obtained.

Composition in percent: P, 27.7; C, 22.1; H, 4.0.

EXAMPLE 13 Under the conditions described in Example 12, 9.32 grams (63millimoles) triethyl orthoformate were added to a mixture of 8.96 grams(63 millimoles) phosphorus pentoxide and 40 cc. chloroform. After 10minutes the reaction mixture was heated for 6 hours at 40 C. Thephosphorus pentoxide dissolved completely. The solvent was evaporated invacuo at a temperature of the bath of 60 C. A colourless oil wasobtained.

Composition in percent: P, 25.8; C, 23.3; H, 5.1.

EXAMPLE 14 1.33 grams (9 millimoles) triethyl orthoformate were added toa mixture at 0 C. of 0.34 grams (44.5 millimoles) phosphorus pentoxideand 30 cc. carbon tetrachloride. The temperature of the reaction mixturewas allowed to rise to room temperature within 15 minutes. The reactionmixture was then shaken for 10 hours at room temperature and thenseparated from unreacted proportions of phosphorus pentoxide by suctionfiltration. The solution was concentrated under a pressure of 0.1millimeter of mercury at a temperature of the bath of 40 C. until aconstant Weight had been obtained. A viscous oil was obtained.

Composition in percent: P, 37.3; C, 22.6; H, 4.9.

EXAMPLE 15 Under the conditions described in Example 12, 22.7 grams (154millimoles) triethyl orthoformate were added to a mixture of 7.32 grams(51.5 millimoles) phosphorus pentoxide and 10 cc. methylene chloride.The temperature of the reaction mixture was allowed to rise to 0 C.within 20 minutes and the reaction mixture was then shaken at thattemperature for 3 hours. The P 0 dissolved completely. The methylenechloride was distilled off in vacuo at a temperature of the bath of 20C. The solution was then heated under a pressure of 0.05 millimeter ofmercury at a temperature of the bath of 40 C. until a constant weightwas obtained. The oil so obtained had the following composition inpercent: P, 16.2; C, 37.4; H, 7.4.

EXAMPLE 16 10 grams (49 millimoles) tetraethyl orthosilicate were addeddropwise to a mixture at 0 C. of 14.2 grams (100 millimoles) phosphoruspentoxide and 20 cc. chloroform under dry nitrogen. During theintroduction of the tetraethyl orthosilicate, the mixture was cooled onan ice water bath. The reaction was strongly exothermic. The P 0 hadreacted within a few minutes. A viscous solution containing insolubleproportions was obtained, which was diluted with 200 cc. chloroform tofacilitate filtration. The reaction mixture was suction-filtered and thesolution was concentrated. A soft amorphous crumbly product wasobtained. The product was comminuted, 200 cc. of a mixture of 2 parts byvolume of heptane and 1 part by volume of chloroform were added and theWhole was shaken for 6 hours. After suction filtration, the solidamorphous white filtrate was freed from solvent in vacuo at atemperature of the bath of C. A white amorphous mass (fraction 1) wasobtained.

Composition in percent: Si, 3.7; P, 19.7; C, 24.7; H, 5.9.

The solid residue left behind in the first suction filtration of thereaction mixture was also cornminuted washed and freed from solvent asdescribed above. A white amorphous mass (fraction II) was obtained.

Composition in percent: Si, 8.1; P, 18.2; C, 11.0; H, 2.6.

Fraction I was sparingly soluble and fraction II difficult- 1y solublein chloroform.

EXAMPLE 17 4.0 grams (1 1.5 millimoles) hexaethyl-di-orthosilicate wereadded to a mixture at 20 C. of 4.70 grams (33 millimoles) phosphoruspentoxide and 20 cc. chloroform and the whole was shaken at roomtemperature for 6 hours. A transparent stiff gel was obtained; the P 0had been consumed quantitatively. The chloroform was evaporated invacuo. A white amorphous mass which was easily soluble in chloroform wasobtained.

Composition in percent: Si, 7.6; P, 21.4; C, 22.3; H, 5.2.

EXAMPLE 18 6.6 grams ethyl polyorthosilicate were added to a mixture at20 C. of 8.07 grams (58 millimoles) P and 20 cc. chloroform and thewhole was shaken for 6 hours at room temperature. The gel-like masswhich had been formed (the P 0 had been consumed quantitatively) wasconcentrated in vacuo. A white amorphous mass was ob tained which waseasily soluble in chlorinated hydrocarbons.

Composition in percent: Si, 3.6; P, 20.9; C, 24.6; H, 5.8.

EXAMPLE 19 6.3 grams (52 millimoles) dimethyl-dimethoxysilane [(CHSi(0CH were added dropwise, while stirring, under dry nitrogen to amixture at 20 C. of 1.45 grams (52 millimoles) P 0 and 20 cc.chloroform. After 20 minutes the temperature of the reaction mixture wasallowed to rise to room temperature. The phosphorus pentoxide reactedquantitatively. The solvent was evaporated in vacuo at a temperature ofthe bath of 40 C. until a constant weight was obtained. A viscouscolourless oil was obtained.

Composition in percent: Si, 9.3; P, 22.7; C, 16.0; H, 4.3.

EXAMPLE 20 Under the conditions described in Example 19, 1.44 grams (12millimoles) dimethyldimethoxysilane were added to a mixture of 6.74grams (47.5 millimoles) phosphorus pentoxide and cc. methylene chloride.After 10 minutes the temperature of the reaction mixture was allowed torise to room temperature and the reaction mixture was shaken for afurther 5 hours. It was then diluted with cc. methylene chloride andseparated from undissolved proportions by suction filtration. 50 cc.heptane were added to the solution whereby an oily colourless productwas precipitated. The supernatant solution was decanted and the oil waswashed and freed from residual proportions of solvent in vacuo asdescribed in Example 3. An amorphous solid White mass was obtained.

Composition in percent: Si, 6.2; P, 32.8; C, 12.4; H, 3.2.

EXAMPLE 21 14.2 grams (130 millimoles) dimethyl sulfite were added,under nitrogen and with the exclusion of moisture, to a mixture of 18.24grams (130 millimoles) phosphorus pentoxide and cc. chloroform and thewhole was heated under reflux for 6 hours at 60 C. The reaction mixturewas separated from unreacted phosphorus pentoxide by suction filtration.The solution was concentrated in vacuo at a temperature of the bath of80 C. until a constant weight was obtained. 20.2 grams of a viscouscolourless oil were obtained.

Composition in percent: S, P, 31.4; C, 14.3; H, 3.7.

10 EXAMPLE 22 In the manner described in Example 21, 7.64 grams (54millimoles) phosphorus pentoxide and 3.58 grams (32 millimoles) dimethylsulfite were reacted in the presence of 10 cc. chloroform. After heatingfor 6 hours at C., the reaction mixture was cooled to room temperatureand 60 cc. of heptane were then added. The oil which had precipitatedwas washed and freed from residual proportions of solvent as describedin Example 6, a viscous colourless oil being obtained.

EXAMPLE 23 19.2 grams (175 millimoles) methanesulfonic acid methyl esterwere added, under nitrogen and with the exclusion of moisture. to amixture of 12.4 grams (87.5 millimoles) phosphorus pentoxide and 10 cc.methylene chloride, and the whole was heated under reflux for 5 hours. Afurther 20 cc. methylene chloride were then added and the solution wasseparated from the solid substance by suction filtration. The filtratewas concentrated to about 10 cc. in vacuo and 50 cc. absolute ether werethen added, whereby a yellowish oil Was precipitated. The oil wasallowed to deposit and the supernatant solution was decanted. The oilwas digested twice with 50 cc. absolute ether and then freed under apressure of 1 millimeter of mercury at a temperature of the bath of 50C., from residual solvent. 18.3 grams of a yellowish viscous oil wereobtained.

Composition in percent: S, 16.8;P, 19.0; C, 12.2; H, 3.2.

We claim:

1. A process for producing neutral polyphosphoric acid ester derivativeswhich comprises reacting an acid ester with phosphorus pentoxide at atemperature within the range of 78 C. to C., in the absence of moistureand in a mole ratio of ester to phosphorus pentoxide from 0.05 to 9moles ester to 1 mole phosphorus pentoxide, said acid ester beingdefined by the general formula (RJmB(OR)n (Rm wherein 1+m+n=3 in whichformula R represents a saturated or oxalkylated aliphatic radical of 1to 12 carbon atoms, or an allyl radical or a phenyl radical. R and R"each represents a hydrogen, a saturated or oxalkylated aliphatic radicalof 1 to 12 carbon atoms or an allyl radical or a phenyl radical.

2. The process of claim 1 wherein trimethylor triethylor tri-n-propylborate or ethylor methyl boric acid-dimethylor diethyl ester or amixture of these compounds is reacted with phosphorus pentoxide.

No references cited.

ALEX MAZEL, Primary Examiner A. H. SUTTO, Assistant Examiner U.S. Cl.X.R. 260615 A, 980

"UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 6.6 m5q6Dated Februarv 22. 1Q72 Invefitofls) Kampe and Fischer I It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

In the Heading} 7 Afterv Ser. No. 8 l-l ,-6 L5" insert ---3 claimspriority of October 28,. 196%, Germany, F M L526."

Signed and sealed this 5th day of December 1972.

( SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents USCOMM-DC 50376-P69 Q U.S. GOVERNMENT PRINTING OFFICE: I9690-366-334 FORM PO-105O (10-69)

